openai/gpt-chat-latest → A (3:2)

Side A introduces a durable URL-routing refactor by centralizing room path encoding/decoding (`room_route_segment`/`room_id_from_route_segment`), updating all route handlers and URL builders to use a single `{short}{slug}` segment, replacing duplicated string-splitting logic, and adding URL normalization utilities and tests for canonical external identities. Side B meaningfully improves vote-pair selection by adding more nuanced bridge priorities and rank-based refinement with supporting tests, but its impact is confined to one subsystem, whereas Side A establishes shared infrastructure used across routing, link generation, canonicalization, and tests.